Directions:

Beat peanut butter, oil, 3/4 cup sugar substitute, and the vanilla with an electric beater until smooth and creamy. Gradually add eggs, beating well with each addition. Beat in banana.

Lightly fold 1/2 cup flour through the peanut mixture. Stir in the buttermilk, followed by the remaining 1/2 cup flour.

Spoon into 12 cupcake cases and bake in preheated oven for 12 to 15 minutes, or until a toothpick inserted into the center comes out clean. Allow to cool for 5 to 10 minutes in pan, then turn onto a wire rack.